MCP - Developer exploring GPT-5.5 Pro's math capabilities and c...

I'm quite Claude-pilled but GPT 5.5 Pro appears to have excellent mathematical reasoning capabilities. Doesn't appear to be usable in Codex though? What gives? Do I need to write an MCP server that lets codex talk to gpt-5.5-pro? Source: https://x.com/KenoFischer/status/2056927373505765735